Various types of passive infra-red sensors are presently being marketed for intrusion detection applications. The Sontrix Passive Infrared Intrusion Detector, manufactured by Ademco of Syosset, N.Y., defines a plurality of protective zones, each of which is defined by its own parabolic reflecting surface. Horizontal and vertical adjustability is provided by suitable positioning of the entire optical head.
Series S8600 Motion Detectors of Arrowhead Enterprises Inc. provides a beam locator whereby an LED illuminates the protective zones, enabling an installer to determine the zones of protection. Since the LED is displaced from the detector, apparatus for focusing the LED beam is required in addition to that used in association with the detector. In the Arrowhead apparatus, beam locator focussing lenses are provided within each of the detector focussing lenses.
The Red-Watch PIR 550 passive infrared sensor manufactured by Napco Security Systems, Inc. of Capiague, N.Y. provides interchangeable lenses but does not provide a built in beam locator.